Material for handling molten glass



3,055,526 Patented Nov. 27, 1962 MATERIAL 1 R NDLING MOLTEN GLASS JamesS. Hill, Cranford, NJ, assignor, by mesne assignments, to EngeihardIndustries, ind, Newark, NJ, a

corporation of Delaware No Drawing. Qriginal application Oct. 25, 1957,Ser.

No. 692,257, new Fatent No. 2,973,283, dated Feb.

28, 1961. Divided and this application Sept. 10, 1958,

Ser. No. 760,061

2 Claims. (Ci. 29199) The present invention deals with an apparatus forhandling molten glass as, for example, glass forming dies or extrusionnozzles for the spinning of glass fibers.

Alloys of platinum with up to about 50 percent rhodium have beensuggested and used for the manufacture of many types of spinning nozzlesfor artificial fibers, these alloys combining the required propertiesfor the purpose, to a large extent, such as hardness and corrosionresistance.

However, for apparatus handling molten glass, such as e.g. glassspinnerettes, a further requirement for satisfactory operation becomesimportant, i.e., the surface which is in contact with the molten glassshould not be Wetted thereby. This requirement is not satisfactorily metby the platinum-rhodium alloys used heretofore. On the other hand, it isknown that platinum-gold alloys show a considerable resistance towetting by molten glass, but they are mechanically insufiicientlyresistant, especially at the high temperature of molten glass.

It has been found that the desired properties of hardness, and ofnon-Wetting by molten glass, can be obtained by depositing, for exampleby electroplating or any other suitable method, a double coating upon anarticle of a platinum-rhodium alloy, which may be the portion of anapparatus which contacts molten glass, such as a spinnerette forspinning glass fibers, a die in a press or the like.

According to the invention, the article is coated with platinum, andthen a coating of gold is applied upon the platinum layer whereupon thearticle is heated to diffusion temperature, preferably by placing it ina furnace at about 800 C. and gradually raising the temperature to about1200 C. The heat treatment causes the metals to diffuse into each otherwhereby, in the different boundary zones, solid solutions are formed,thus insuring that the coatings adhere firmly to each other and to theplatinum-rhodium surface.

The coatings of platinum and gold may be in the range of about 0.0001 toabout 0.001 inch and good results have been obtained with layers ofabout 0.0005 inch.

Moreover, it has been found by tests made with platinum-rhodium alloyscontaining percent to 40 percent by weight rhodium that the surfacesobtained display a combination of properties which the single componentsdo not show. The surfaces are extremely repellent to molten glass, dueto the predominating content of gold in the outer layer, wherein someplatinum but practically no rhodium is present, but at the same time thehardness is increased beyond the hardness the original platinumrhodiumalloy would have attained, when subjected to the same heat treatment,without being coated or if coated with one of the components only.

It is believed that this result is due to the formation of solidsolutions which are gradually enriched in gold near the surface whereasan increasing content of rhodium is present deeper in the metal. Theintermediate layer of platinum prevents undesirable diffusion betweenthe rhodium content of the alloy and the gold coating, thus actingsimultaneously as a buffer and as a bonding agent between theplatinum-rhodium alloy and the gold layer.

it will be obvious to those skilled in the art that many modificationsmay be made within the scope of the present invention without departingfrom the spirit thereof, and

the invention includes all such modifications.

This application is a division of co-pending application Serial No.692,257 fiied October 25, 1957, now Patent No. 2,973,283.

What is claimed is:

1. A material for handling molten glass and resistant to wetting bymolten glass, composed of an alloy of platinum and from 10 percent to 50percent rhodium with a coating on a surface thereof composed ofinterdifiused layers of platinum and gold with the platinum on theplatinum-rhodium surface and the gold on the platinum and each of thelayers having a thickness of up to 0.001", and the surface of thecoating having a hardness at least equal to the platinum-rhodium alloy.

2. A material according to claim -1, wherein the platinum and goldlayers are electroplated layers.

References Cited in the file of this patent UNITED STATES PATENTS111,551 Kearsing Feb. 7, 1871 145,274 Blake Dec. 9, 1873 1,460,888 CookJuly 3, 1923 1,659,757 Aderer Feb. 21, 1928 1,704,126 Fry Mar. 5, 19291,947,180 Bart Feb. 13, 1934 1,963,910 McIntyre June 19, 1934 2,106,527Hostetter Jan. 25, 1938 2,190,296 Richardson Feb. 13, 1940 2,391,457Carlson Dec. 25, 1945 2,460,547 Stevens Feb. 1, 1949 2,803,925 KlausmannAug. 27, 1957 2,949,633 Drummon Aug. 23, 1960

1. A MATERIAL FOR HANDLING MOLTEN GLASS AND RESISTANT TO WETTING BYMOLTEN GLASS, COMPOSED OF AN ALLOY OF PLATINUM AND FROM 10 PERCENT TO 50PERCENT RHODIUM WITH A COATING ON A SURFACE THEREOF COMPOSED OFINTERDIFFUSED LAYERS OF PLATINUM AND GOLD WITH THE PLATINUM ON THEPLATINUM-RHODIUM SURFACE AND THE GOLD ON THE PLATINUM AND EACH OF THELAYERS HAVING A THICKNESS OF UP TO 0.001", AND THE SURFACE OF THECOATING HAVING A HARDNESS AT LEAST EQUAL TO THE PLATINUM-RHODIUM ALLOY.